Characterization of Alterations of Hemodynamics and Neuroendocrine Hormones in Dexamethasone Induced Hypertension in Dogs

The serial changes in systemic and renal hemodynamics, water and electrolyte balances and various vasoactive hormones were examined in 12 conscious dogs before, during (10 days) the administration of dexamethasone (DEX: 0.5mg/kg/day) and after the cessation of DEX. In addition, during the administration of DEX, pressor responses to angiotensin II, norepinephrine, an angiotensin II analogue, saralasin, and an alpha-1-blocker, prazosin, were studied. Abrupt elevation of blood pressure to 106±5 mmHg on Day 1 (vs. 91±6 mmHg control :P<0.05) associated with marked increases in total peripheral resistance (P<0.01) was shown in DEX treated animals. Accompanied with these changes, renal blood flow increased to 146±12 ml/min (vs. 103±8 ml/min control: P<0.05) on Day 1 and maintained. In contrast, the results of serial alterations in hormones could not show any significant changes except significant elevations in atrial natriuretic peptide and reductions of cortisol and arginine vasopressin. Also, marked natriuresi...